Abstract 4518: PCL/Maltodextrin delivered ID4 maintains its tumor suppressor role.

Abstract

Abstract INTRODUCTION: The Inhibitor of differentiation protein (Id) family has generated much attention in cancer cell biology due to its multifaceted role. These proteins have a helix–loop– helix (HLH) domain required for association with transcriptional factors but lack the basic amino acids required for DNA-binding therefore act as dominant-negative regulators of transcription. Tumor suppressor roles have been strongly associated with Id4 one of the four different isoforms identified so far. A recent study by Chaudhary et al indicated that Id4 was a potential tumor suppressor of prostate cancer with ectopic expression of Id4 in DU145 leading to increased apoptosis and decreased cell proliferation due in part by an S-phase arrest. Methylation mediated silencing of the Id4 gene has been associated with development of prostate cancer. In this study we evaluated the pro-apoptotic potential of intracellularly delivered Id4 using PCL/Maltodextrin nanoparticles as the delivery vector. METHOD: PCL/Maltodextrin nanoparticles were formulated using the double emulsion solvent evaporation technique with a Nano Debee high-pressure homogenizer. Nanoparticles were lyophilized and characterized for their size, zeta potential, and encapsulation efficiency. Western blot analysis was conducted on Id4 loaded nanoparticles and nanoparticle treated DU 145 cell lines to confirm the presence and delivery of intact protein. Immuno-cytochemical analysis of Id4 expression was conducted on DU-145, LNCaP and LNCaP cells silenced with Id4 (LNCaP-Id4) pre and post treatment with Id4 loaded nanoparticles.The effect of nanoparticle delivered Id4 on cellular processes such as apoptosis, proliferation and transwell migration was also determined. RESULTS: Id4 loaded PCL/Maltodextrin nanoparticles was successfully formulated with an average particle size of about 200nm. The formulation had encapsulation efficiency of 78.83±7.40% and percentage yield over 98%. Western blot analysis reveals that intact Id4 protein was successfully loaded and delivered to the cells. Immuno-cytochemical analysis of the three cell lines showed an efficient intracellular delivery of Id4 using PL/Maltodextrin with the intracellular amount increasing with time. The ICC analysis also showed possible intra- nuclear localization of Id4. Intracellular delivered Id4 increased the levels of Caspase 3/9 by about three folds associated with decreased mitochondrial membrane potential and plasma membrane asymmetry. The transwell migration assay also showed a significant decrease in cell migration after treatment with Id4 loaded nanoparticles in comparison to the untreated and blank nanoparticle group. CONCLUSION: PCL/Maltodextrin nanocarrier can successfully deliver Id4 to the cytoplasm as well as nucleus of LNCaP-Id4, DU145 and LNCaP. Intracellular delivered Id4 maintains it pro apoptotic potential. Citation Format: Maxwell Korang-Yeboah, Pankaj Sharma, Ashley Evans Knowell, Divya Patel, Yamini Gorantla, Swathi Chinaranagari, Ravi Palaniappa, Jaideep Chaudhary. PCL/Maltodextrin delivered ID4 maintains its tumor suppressor role. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4518. doi:10.1158/1538-7445.AM2013-4518